Keoke
Gold Member
Hi guys, if the oil & compression ring gaps happen to be on the bottom of piston when the engine is shut down some oil will end up in the combustion chamber on startup.
This is comon to opposed engines that have a lot of splash oiling taking place above the pistons.
On radial engines (aircraft) the bottom cylinders sometimes need to drained of oil before start up because of the same condition will get bad enough to cause cyl hydro lock.
Some opposed engines will have pins in the piston ring grooves to keep all the rings gaps in a staggerd up (9 to 3 O'clock) position. This keeps all the ring grooves up but prevents ring rotation. Pining is good for oil control but not the best thing for cyl wear.
cheers,
This is comon to opposed engines that have a lot of splash oiling taking place above the pistons.
On radial engines (aircraft) the bottom cylinders sometimes need to drained of oil before start up because of the same condition will get bad enough to cause cyl hydro lock.
Some opposed engines will have pins in the piston ring grooves to keep all the rings gaps in a staggerd up (9 to 3 O'clock) position. This keeps all the ring grooves up but prevents ring rotation. Pining is good for oil control but not the best thing for cyl wear.
cheers,